<!DOCTYPE html>
<html lang="en-US">
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width,initial-scale=1">
    <title>Swift 命名空间 | KnightSama‘s Blog</title>
    <meta name="description" content="Hello, my friend!">
    <link rel="icon" href="/favicon.ico">
  <meta name="viewport" content="width=device-width,initial-scale=1,user-scalable=no">
  <script src="https://cdn.jsdelivr.net/npm/react/umd/react.production.min.js"></script>
  <script src="https://cdn.jsdelivr.net/npm/react-dom/umd/react-dom.production.min.js"></script>
  <script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.min.js"></script>
  <script src="https://cdn.jsdelivr.net/npm/@babel/standalone/babel.min.js"></script>
    
    <link rel="preload" href="/assets/css/0.styles.c4ea52a5.css" as="style"><link rel="preload" href="/assets/js/app.a2483de7.js" as="script"><link rel="preload" href="/assets/js/4.0078dadf.js" as="script"><link rel="preload" href="/assets/js/1.c3e7d2b0.js" as="script"><link rel="preload" href="/assets/js/27.6ee3d263.js" as="script"><link rel="prefetch" href="/assets/js/10.265e4f40.js"><link rel="prefetch" href="/assets/js/11.a3a2f8c1.js"><link rel="prefetch" href="/assets/js/12.1910f8cc.js"><link rel="prefetch" href="/assets/js/13.229fa478.js"><link rel="prefetch" href="/assets/js/14.c27d4a17.js"><link rel="prefetch" href="/assets/js/15.92adafd4.js"><link rel="prefetch" href="/assets/js/16.bcee7c14.js"><link rel="prefetch" href="/assets/js/17.ee1bcf41.js"><link rel="prefetch" href="/assets/js/18.fa3c3a4e.js"><link rel="prefetch" href="/assets/js/19.1a943c57.js"><link rel="prefetch" href="/assets/js/20.44781dae.js"><link rel="prefetch" href="/assets/js/21.1fe46223.js"><link rel="prefetch" href="/assets/js/22.6f7d46c2.js"><link rel="prefetch" href="/assets/js/23.56223d02.js"><link rel="prefetch" href="/assets/js/24.e7cad43b.js"><link rel="prefetch" href="/assets/js/25.b2902552.js"><link rel="prefetch" href="/assets/js/26.70698c07.js"><link rel="prefetch" href="/assets/js/28.ce131de6.js"><link rel="prefetch" href="/assets/js/29.90552487.js"><link rel="prefetch" href="/assets/js/30.b3291ccc.js"><link rel="prefetch" href="/assets/js/31.ea8c441e.js"><link rel="prefetch" href="/assets/js/32.3e29bbeb.js"><link rel="prefetch" href="/assets/js/33.65e78c5e.js"><link rel="prefetch" href="/assets/js/34.3ba19d7c.js"><link rel="prefetch" href="/assets/js/35.66d3fc4a.js"><link rel="prefetch" href="/assets/js/36.f5725281.js"><link rel="prefetch" href="/assets/js/37.f5b0b5ff.js"><link rel="prefetch" href="/assets/js/38.3cae3054.js"><link rel="prefetch" href="/assets/js/39.47dc1ffe.js"><link rel="prefetch" href="/assets/js/5.f0714e2e.js"><link rel="prefetch" href="/assets/js/6.53240a5f.js"><link rel="prefetch" href="/assets/js/7.dc126a6b.js"><link rel="prefetch" href="/assets/js/8.86452400.js"><link rel="prefetch" href="/assets/js/9.16ef06de.js"><link rel="prefetch" href="/assets/js/vendors~flowchart.734d5d92.js">
    <link rel="stylesheet" href="/assets/css/0.styles.c4ea52a5.css">
  </head>
  <body>
    <div id="app" data-server-rendered="true"><div><div class="theme-container" data-v-0cb1c278><div data-v-0cb1c278><div id="loader-wrapper" class="loading-wrapper" data-v-4b73742e data-v-0cb1c278 data-v-0cb1c278><div class="loader-main" data-v-4b73742e><div data-v-4b73742e></div><div data-v-4b73742e></div><div data-v-4b73742e></div><div data-v-4b73742e></div></div> <!----> <!----></div> <div class="password-shadow password-wrapper-out" style="display:none;" data-v-da0660ba data-v-0cb1c278 data-v-0cb1c278><h3 class="title" style="display:none;" data-v-da0660ba data-v-da0660ba>KnightSama‘s Blog</h3> <!----> <label id="box" class="inputBox" style="display:none;" data-v-da0660ba data-v-da0660ba><input type="password" value="" data-v-da0660ba> <span data-v-da0660ba>Konck! Knock!</span> <button data-v-da0660ba>OK</button></label> <div class="footer" style="display:none;" data-v-da0660ba data-v-da0660ba><span data-v-da0660ba><i class="iconfont reco-theme" data-v-da0660ba></i> <a target="blank" href="https://vuepress-theme-reco.recoluan.com" data-v-da0660ba>vuePress-theme-reco</a></span> <span data-v-da0660ba><i class="iconfont reco-copyright" data-v-da0660ba></i> <a data-v-da0660ba><span data-v-da0660ba>KnightSama</span>
            
          <!---->
          2021
        </a></span></div></div> <div class="hide" data-v-0cb1c278><header class="navbar" data-v-0cb1c278><div class="sidebar-button"><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" role="img" viewBox="0 0 448 512" class="icon"><path fill="currentColor" d="M436 124H12c-6.627 0-12-5.373-12-12V80c0-6.627 5.373-12 12-12h424c6.627 0 12 5.373 12 12v32c0 6.627-5.373 12-12 12zm0 160H12c-6.627 0-12-5.373-12-12v-32c0-6.627 5.373-12 12-12h424c6.627 0 12 5.373 12 12v32c0 6.627-5.373 12-12 12zm0 160H12c-6.627 0-12-5.373-12-12v-32c0-6.627 5.373-12 12-12h424c6.627 0 12 5.373 12 12v32c0 6.627-5.373 12-12 12z"></path></svg></div> <a href="/" class="home-link router-link-active"><img src="/Misaka.jpg" alt="KnightSama‘s Blog" class="logo"> <span class="site-name">KnightSama‘s Blog</span></a> <div class="links"><div class="color-picker"><a class="color-button"><i class="iconfont reco-color"></i></a> <div class="color-picker-menu" style="display:none;"><div class="mode-options"><h4 class="title">Choose mode</h4> <ul class="color-mode-options"><li class="dark">dark</li><li class="auto active">auto</li><li class="light">light</li></ul></div></div></div> <div class="search-box"><i class="iconfont reco-search"></i> <input aria-label="Search" autocomplete="off" spellcheck="false" value=""> <!----></div> <nav class="nav-links can-hide"><div class="nav-item"><a href="/" class="nav-link"><i class="iconfont reco-home"></i>
  首页
</a></div><div class="nav-item"><div class="dropdown-wrapper"><a class="dropdown-title"><span class="title"><i class="iconfont reco-category"></i>
      分类
    </span> <span class="arrow right"></span></a> <ul class="nav-dropdown" style="display:none;"><li class="dropdown-item"><!----> <a href="/categories/iOS/" class="nav-link"><i class="iconfont undefined"></i>
  iOS
</a></li><li class="dropdown-item"><!----> <a href="/categories/集锦/" class="nav-link"><i class="iconfont undefined"></i>
  集锦
</a></li><li class="dropdown-item"><!----> <a href="/categories/JavaScript/" class="nav-link"><i class="iconfont undefined"></i>
  JavaScript
</a></li><li class="dropdown-item"><!----> <a href="/categories/Github/" class="nav-link"><i class="iconfont undefined"></i>
  Github
</a></li><li class="dropdown-item"><!----> <a href="/categories/Python/" class="nav-link"><i class="iconfont undefined"></i>
  Python
</a></li></ul></div></div><div class="nav-item"><a href="/tag/" class="nav-link"><i class="iconfont reco-tag"></i>
  标签
</a></div><div class="nav-item"><a href="/timeline/" class="nav-link"><i class="iconfont reco-date"></i>
  时间线
</a></div><div class="nav-item"><a href="https://github.com/KnightSama" target="_blank" rel="noopener noreferrer" class="nav-link external"><i class="iconfont reco-github"></i>
  GitHub
  <svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15" class="icon outbound"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path> <polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg></a></div> <!----></nav></div></header> <div class="sidebar-mask" data-v-0cb1c278></div> <aside class="sidebar" data-v-0cb1c278><div class="personal-info-wrapper" data-v-4a3def3c><img src="/Misaka.jpg" alt="author-avatar" class="personal-img" data-v-4a3def3c> <h3 class="name" data-v-4a3def3c>
    KnightSama
  </h3> <div class="num" data-v-4a3def3c><div data-v-4a3def3c><h3 data-v-4a3def3c>27</h3> <h6 data-v-4a3def3c>文章</h6></div> <div data-v-4a3def3c><h3 data-v-4a3def3c>14</h3> <h6 data-v-4a3def3c>标签</h6></div></div> <hr data-v-4a3def3c></div> <nav class="nav-links"><div class="nav-item"><a href="/" class="nav-link"><i class="iconfont reco-home"></i>
  首页
</a></div><div class="nav-item"><div class="dropdown-wrapper"><a class="dropdown-title"><span class="title"><i class="iconfont reco-category"></i>
      分类
    </span> <span class="arrow right"></span></a> <ul class="nav-dropdown" style="display:none;"><li class="dropdown-item"><!----> <a href="/categories/iOS/" class="nav-link"><i class="iconfont undefined"></i>
  iOS
</a></li><li class="dropdown-item"><!----> <a href="/categories/集锦/" class="nav-link"><i class="iconfont undefined"></i>
  集锦
</a></li><li class="dropdown-item"><!----> <a href="/categories/JavaScript/" class="nav-link"><i class="iconfont undefined"></i>
  JavaScript
</a></li><li class="dropdown-item"><!----> <a href="/categories/Github/" class="nav-link"><i class="iconfont undefined"></i>
  Github
</a></li><li class="dropdown-item"><!----> <a href="/categories/Python/" class="nav-link"><i class="iconfont undefined"></i>
  Python
</a></li></ul></div></div><div class="nav-item"><a href="/tag/" class="nav-link"><i class="iconfont reco-tag"></i>
  标签
</a></div><div class="nav-item"><a href="/timeline/" class="nav-link"><i class="iconfont reco-date"></i>
  时间线
</a></div><div class="nav-item"><a href="https://github.com/KnightSama" target="_blank" rel="noopener noreferrer" class="nav-link external"><i class="iconfont reco-github"></i>
  GitHub
  <svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15" class="icon outbound"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path> <polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg></a></div> <!----></nav>  <ul class="sidebar-links"><li><section class="sidebar-group depth-0"><p class="sidebar-heading open"><span>Swift 命名空间</span> <!----></p> <ul class="sidebar-links sidebar-group-items"><li><a href="/Views/20200319.html#三方库中的命名空间" class="sidebar-link">三方库中的命名空间</a><ul class="sidebar-sub-headers"><li class="sidebar-sub-header"><a href="/Views/20200319.html#rxswift-中的命名空间" class="sidebar-link">RxSwift 中的命名空间</a></li><li class="sidebar-sub-header"><a href="/Views/20200319.html#kingfisher-中的命名空间" class="sidebar-link">KingFisher 中的命名空间</a></li></ul></li><li><a href="/Views/20200319.html#命名空间的原理" class="sidebar-link">命名空间的原理</a><ul class="sidebar-sub-headers"></ul></li><li><a href="/Views/20200319.html#命名空间的初步实现" class="sidebar-link">命名空间的初步实现</a><ul class="sidebar-sub-headers"></ul></li><li><a href="/Views/20200319.html#命名空间的最终实现" class="sidebar-link">命名空间的最终实现</a><ul class="sidebar-sub-headers"></ul></li></ul></section></li></ul> </aside> <div class="password-shadow password-wrapper-in" style="display:none;" data-v-da0660ba data-v-0cb1c278><h3 class="title" style="display:none;" data-v-da0660ba data-v-da0660ba>Swift 命名空间</h3> <!----> <label id="box" class="inputBox" style="display:none;" data-v-da0660ba data-v-da0660ba><input type="password" value="" data-v-da0660ba> <span data-v-da0660ba>Konck! Knock!</span> <button data-v-da0660ba>OK</button></label> <div class="footer" style="display:none;" data-v-da0660ba data-v-da0660ba><span data-v-da0660ba><i class="iconfont reco-theme" data-v-da0660ba></i> <a target="blank" href="https://vuepress-theme-reco.recoluan.com" data-v-da0660ba>vuePress-theme-reco</a></span> <span data-v-da0660ba><i class="iconfont reco-copyright" data-v-da0660ba></i> <a data-v-da0660ba><span data-v-da0660ba>KnightSama</span>
            
          <!---->
          2021
        </a></span></div></div> <div data-v-0cb1c278><main class="page"><div class="sidebar-open-close"><svg xmlns="http://www.w3.org/2000/svg" role="img" viewBox="0 0 448 512" class="icon"><path fill="currentColor" d="M436 124H12c-6.627 0-12-5.373-12-12V80c0-6.627 5.373-12 12-12h424c6.627 0 12 5.373 12 12v32c0 6.627-5.373 12-12 12zm0 160H12c-6.627 0-12-5.373-12-12v-32c0-6.627 5.373-12 12-12h424c6.627 0 12 5.373 12 12v32c0 6.627-5.373 12-12 12zm0 160H12c-6.627 0-12-5.373-12-12v-32c0-6.627 5.373-12 12-12h424c6.627 0 12 5.373 12 12v32c0 6.627-5.373 12-12 12z"></path></svg></div> <!----> <div class="page-title" style="display:none;"><h1>Swift 命名空间</h1> <hr> <div data-v-73367bb4><i class="iconfont reco-account" data-v-73367bb4><span data-v-73367bb4>KnightSama</span></i> <i class="iconfont reco-date" data-v-73367bb4><span data-v-73367bb4>2020-03-19</span></i> <i class="iconfont reco-eye" data-v-73367bb4><span id="/Views/20200319.html" data-flag-title="Your Article Title" class="leancloud-visitors" data-v-73367bb4><a class="leancloud-visitors-count" style="font-size:.9rem;font-weight:normal;color:#999;"></a></span></i> <i class="iconfont reco-tag tags" data-v-73367bb4><span class="tag-item" data-v-73367bb4>
      Swift
    </span></i></div></div> <div class="theme-reco-content content__default" style="display:none;"><p>Objective-C 一个一直以来令人诟病的地方就是没有命名空间，在应用开发时，所有的代码和引用的静态库最终都会被编译到同一个域和二进制中。这样的后果是一旦我们有重复的类名的话，就会导致编译时的冲突和失败。为了避免这种事情的发生，Objective-C 的类型一般都会加上两到三个字母的前缀。在 Swift 中，由于可以使用命名空间了，即使是名字相同的类型，只要是来自不同的命名空间的话，都是可以和平共处的。
</p> <h2 id="三方库中的命名空间"><a href="#三方库中的命名空间" class="header-anchor">#</a> 三方库中的命名空间</h2> <p>在一些三方库中经常可以看到命名空间的使用</p> <h3 id="rxswift-中的命名空间"><a href="#rxswift-中的命名空间" class="header-anchor">#</a> RxSwift 中的命名空间</h3> <p>当我们在使用 RxSwift 时经常用到下面的方法</p> <div class="language-swift line-numbers-mode"><pre class="language-swift"><code><span class="token keyword">let</span> observable <span class="token operator">=</span> textField<span class="token punctuation">.</span>rx<span class="token punctuation">.</span>text<span class="token punctuation">.</span>orEmpty<span class="token punctuation">.</span><span class="token function">asObservable</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><p>其中的  <code>rx</code>  就是 RxSwift 的命名空间</p> <h3 id="kingfisher-中的命名空间"><a href="#kingfisher-中的命名空间" class="header-anchor">#</a> KingFisher 中的命名空间</h3> <p>当我们在使用 KingFisher 时会用到下面的方法</p> <div class="language-swift line-numbers-mode"><pre class="language-swift"><code>imageView<span class="token punctuation">.</span>kf<span class="token punctuation">.</span><span class="token function">setImage</span><span class="token punctuation">(</span>with<span class="token punctuation">:</span> <span class="token function">URL</span><span class="token punctuation">(</span>string<span class="token punctuation">:</span> url<span class="token punctuation">)</span><span class="token punctuation">)</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><p>其中的  <code>kf</code>  就是 KingFisher 的命名空间</p> <h2 id="命名空间的原理"><a href="#命名空间的原理" class="header-anchor">#</a> 命名空间的原理</h2> <p>如果我们想给 UIView 添加一个 width 属性来获得视图的宽度，我们可以通过 extension 来给 UIView 添加一个名字为 width 的计算属性，这样可以通过下面的方式使用</p> <div class="language-swift line-numbers-mode"><pre class="language-swift"><code><span class="token keyword">let</span> width <span class="token operator">=</span> <span class="token keyword">self</span><span class="token punctuation">.</span>view<span class="token punctuation">.</span>width
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><p>但是如果使用了其他的三方库很容易造成冲突，如果按照 Objective-C 的解决思路是添加前缀，这样就变成</p> <div class="language-swift line-numbers-mode"><pre class="language-swift"><code><span class="token keyword">let</span> width <span class="token operator">=</span> <span class="token keyword">self</span><span class="token punctuation">.</span>view<span class="token punctuation">.</span>ks_width
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><p>这样虽然可以解决问题但并不优雅，并且也有一定几率重复，我们的目标是变成这样</p> <div class="language-swift line-numbers-mode"><pre class="language-swift"><code><span class="token keyword">let</span> width <span class="token operator">=</span> <span class="token keyword">self</span><span class="token punctuation">.</span>view<span class="token punctuation">.</span>ks<span class="token punctuation">.</span>width
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><p>ks 就相当于我们的命名空间，这样就防止了冲突，我们应该如何实现呢。通过上面的代码我们可以看出 ks 应该是 view 中的属性，width 是 ks 中的属性，也就是 ks 是个数据结构，里面包含着我们要扩展的属性与方法，同时将这个数据结构作为属性扩展到我们想扩展的结构上去。同时为了让这个数据结构可以访问到我们要扩展的数据结构中的属性与方法，这个数据结构应该包含原始的数据结构。</p> <h2 id="命名空间的初步实现"><a href="#命名空间的初步实现" class="header-anchor">#</a> 命名空间的初步实现</h2> <div class="language-swift line-numbers-mode"><pre class="language-swift"><code><span class="token comment">/// 创建命名空间</span>
<span class="token keyword">struct</span> <span class="token builtin">NameSpace</span> <span class="token punctuation">{</span>
    <span class="token keyword">private</span> <span class="token keyword">let</span> view<span class="token punctuation">:</span> <span class="token builtin">UIView</span>
    <span class="token keyword">init</span><span class="token punctuation">(</span>view<span class="token punctuation">:</span> <span class="token builtin">UIView</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
        <span class="token keyword">self</span><span class="token punctuation">.</span>view <span class="token operator">=</span> view
    <span class="token punctuation">}</span>
<span class="token punctuation">}</span>

<span class="token comment">/// 为 UIView 添加命名空间</span>
<span class="token keyword">extension</span> <span class="token builtin">UIView</span> <span class="token punctuation">{</span>
    <span class="token keyword">var</span> ks<span class="token punctuation">:</span> <span class="token builtin">NameSpace</span> <span class="token punctuation">{</span>
        <span class="token function">NameSpace</span><span class="token punctuation">(</span>view<span class="token punctuation">:</span> <span class="token keyword">self</span><span class="token punctuation">)</span>
    <span class="token punctuation">}</span>
<span class="token punctuation">}</span>

<span class="token comment">/// 给命名空间添加要添加的属性</span>
<span class="token keyword">extension</span> <span class="token builtin">NameSpace</span> <span class="token punctuation">{</span>
    <span class="token keyword">var</span> width<span class="token punctuation">:</span> <span class="token builtin">CGFloat</span> <span class="token punctuation">{</span>
        <span class="token keyword">self</span><span class="token punctuation">.</span>view<span class="token punctuation">.</span>frame<span class="token punctuation">.</span>width
    <span class="token punctuation">}</span>
<span class="token punctuation">}</span>

<span class="token comment">/// 使用命名空间</span>
<span class="token keyword">let</span> width <span class="token operator">=</span> <span class="token function">UIView</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">.</span>ks<span class="token punctuation">.</span>width
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br></div></div><p>这样我们就为 UIView 增加了一个命名空间，只需要扩展命名空间的属性与方法就可以了，不过这个实现只能针对 UIView 如果是其他的类型就需要重新设计，解决这个问题只需要将上面的命名空间改为泛型版本</p> <div class="language-swift line-numbers-mode"><pre class="language-swift"><code><span class="token comment">/// 创建泛型命名空间</span>
<span class="token keyword">struct</span> <span class="token builtin">NameSpace</span><span class="token operator">&lt;</span><span class="token builtin">Base</span><span class="token operator">&gt;</span> <span class="token punctuation">{</span>
    <span class="token keyword">private</span> <span class="token keyword">let</span> base<span class="token punctuation">:</span> <span class="token builtin">Base</span>
    
    <span class="token keyword">init</span><span class="token punctuation">(</span>base<span class="token punctuation">:</span> <span class="token builtin">Base</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
        <span class="token keyword">self</span><span class="token punctuation">.</span>base <span class="token operator">=</span> base
    <span class="token punctuation">}</span>
<span class="token punctuation">}</span>

<span class="token comment">/// 为 UIView 添加命名空间</span>
<span class="token keyword">extension</span> <span class="token builtin">UIView</span> <span class="token punctuation">{</span>
    <span class="token keyword">var</span> ks<span class="token punctuation">:</span> <span class="token builtin">NameSpace</span><span class="token operator">&lt;</span><span class="token builtin">UIView</span><span class="token operator">&gt;</span> <span class="token punctuation">{</span>
        <span class="token function">NameSpace</span><span class="token punctuation">(</span>base<span class="token punctuation">:</span> <span class="token keyword">self</span><span class="token punctuation">)</span>
    <span class="token punctuation">}</span>
<span class="token punctuation">}</span>

<span class="token comment">/// 给命名空间添加要添加的属性</span>
<span class="token keyword">extension</span> <span class="token builtin">NameSpace</span> <span class="token keyword">where</span> <span class="token builtin">Base</span><span class="token punctuation">:</span> <span class="token builtin">UIView</span> <span class="token punctuation">{</span>
    <span class="token keyword">var</span> width<span class="token punctuation">:</span> <span class="token builtin">CGFloat</span> <span class="token punctuation">{</span>
        <span class="token keyword">self</span><span class="token punctuation">.</span>base<span class="token punctuation">.</span>frame<span class="token punctuation">.</span>width
    <span class="token punctuation">}</span>
<span class="token punctuation">}</span>

<span class="token comment">/// 使用命名空间</span>
<span class="token keyword">let</span> width <span class="token operator">=</span> <span class="token function">UIView</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">.</span>ks<span class="token punctuation">.</span>width
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br><span class="line-number">25</span><br></div></div><p>这样我们实现了一个简单的泛型命名空间，实际上我们发现为 UIView 添加命名空间的过程对任意数据结构都相同，我们可以通过构建一个协议来简化这一过程，同时上面的实现没有考虑到静态属性与方法的扩展问题。</p> <h2 id="命名空间的最终实现"><a href="#命名空间的最终实现" class="header-anchor">#</a> 命名空间的最终实现</h2> <div class="language-swift line-numbers-mode"><pre class="language-swift"><code><span class="token comment">/// 创建泛型命名空间</span>
<span class="token keyword">struct</span> <span class="token builtin">NameSpace</span><span class="token operator">&lt;</span><span class="token builtin">Base</span><span class="token operator">&gt;</span> <span class="token punctuation">{</span>
    <span class="token keyword">private</span> <span class="token keyword">let</span> base<span class="token punctuation">:</span> <span class="token builtin">Base</span>
    
    <span class="token keyword">init</span><span class="token punctuation">(</span>base<span class="token punctuation">:</span> <span class="token builtin">Base</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
        <span class="token keyword">self</span><span class="token punctuation">.</span>base <span class="token operator">=</span> base
    <span class="token punctuation">}</span>
<span class="token punctuation">}</span>

<span class="token comment">/// 创建泛型协议</span>
<span class="token keyword">protocol</span> <span class="token builtin">NameSpaceProtocol</span> <span class="token punctuation">{</span>
    <span class="token comment">/// 关联类型</span>
    associatedtype <span class="token builtin">ProtocolType</span>
    <span class="token comment">/// 实例调用</span>
    <span class="token keyword">var</span> ks<span class="token punctuation">:</span> <span class="token builtin">ProtocolType</span> <span class="token punctuation">{</span><span class="token keyword">get</span><span class="token punctuation">}</span>
    <span class="token comment">/// 静态调用</span>
    <span class="token keyword">static</span> <span class="token keyword">var</span> ks<span class="token punctuation">:</span> <span class="token builtin">ProtocolType</span><span class="token punctuation">.</span><span class="token keyword">Type</span> <span class="token punctuation">{</span><span class="token keyword">get</span><span class="token punctuation">}</span>
<span class="token punctuation">}</span>

<span class="token comment">/// 默认实现泛型协议</span>
<span class="token keyword">extension</span> <span class="token builtin">NameSpaceProtocol</span> <span class="token punctuation">{</span>
    
    <span class="token keyword">var</span> ks<span class="token punctuation">:</span> <span class="token builtin">NameSpace</span><span class="token operator">&lt;</span><span class="token keyword">Self</span><span class="token operator">&gt;</span> <span class="token punctuation">{</span>
        <span class="token builtin">NameSpace</span><span class="token operator">&lt;</span><span class="token keyword">Self</span><span class="token operator">&gt;</span><span class="token punctuation">(</span>base<span class="token punctuation">:</span> <span class="token keyword">self</span><span class="token punctuation">)</span>
    <span class="token punctuation">}</span>
    
    <span class="token keyword">static</span> <span class="token keyword">var</span> ks<span class="token punctuation">:</span> <span class="token builtin">NameSpace</span><span class="token operator">&lt;</span><span class="token keyword">Self</span><span class="token operator">&gt;</span><span class="token punctuation">.</span><span class="token keyword">Type</span> <span class="token punctuation">{</span>
        <span class="token builtin">NameSpace</span><span class="token operator">&lt;</span><span class="token keyword">Self</span><span class="token operator">&gt;</span><span class="token punctuation">.</span><span class="token keyword">self</span>
    <span class="token punctuation">}</span>
    
<span class="token punctuation">}</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br><span class="line-number">25</span><br><span class="line-number">26</span><br><span class="line-number">27</span><br><span class="line-number">28</span><br><span class="line-number">29</span><br><span class="line-number">30</span><br><span class="line-number">31</span><br></div></div><p>命名空间的使用</p> <div class="language-swift line-numbers-mode"><pre class="language-swift"><code><span class="token comment">/// 为 UIView 添加命名空间</span>
<span class="token keyword">extension</span> <span class="token builtin">UIView</span><span class="token punctuation">:</span> <span class="token builtin">NameSpaceProtocol</span> <span class="token punctuation">{</span><span class="token punctuation">}</span>

<span class="token comment">/// 给命名空间添加要添加的属性或方法</span>
<span class="token keyword">extension</span> <span class="token builtin">NameSpace</span> <span class="token keyword">where</span> <span class="token builtin">Base</span><span class="token punctuation">:</span> <span class="token builtin">UIView</span> <span class="token punctuation">{</span>
    <span class="token keyword">var</span> width<span class="token punctuation">:</span> <span class="token builtin">CGFloat</span> <span class="token punctuation">{</span>
        <span class="token keyword">self</span><span class="token punctuation">.</span>base<span class="token punctuation">.</span>frame<span class="token punctuation">.</span>width
    <span class="token punctuation">}</span>
    
    <span class="token keyword">static</span> <span class="token keyword">func</span> <span class="token function">test</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
        <span class="token function">print</span><span class="token punctuation">(</span><span class="token string">&quot;测试静态方法&quot;</span><span class="token punctuation">)</span>
    <span class="token punctuation">}</span>
<span class="token punctuation">}</span>

<span class="token comment">/// 使用命名空间</span>
<span class="token keyword">let</span> width <span class="token operator">=</span> <span class="token function">UIView</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">.</span>ks<span class="token punctuation">.</span>width

<span class="token builtin">UIView</span><span class="token punctuation">.</span>ks<span class="token punctuation">.</span><span class="token function">test</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br></div></div></div> <footer class="page-edit" style="display:none;"><!----> <!----></footer> <!----> <!----></main> <!----> <div class="comments-wrapper" data-v-0cb1c278><div class="valine-wrapper"><div id="valine"></div></div></div></div></div></div></div></div><div class="global-ui"><div class="back-to-ceiling" style="right:1rem;bottom:6rem;width:2.5rem;height:2.5rem;border-radius:.25rem;line-height:2.5rem;display:none;" data-v-a81d141e data-v-a81d141e><svg t="1574745035067" viewBox="0 0 1024 1024" version="1.1" xmlns="http://www.w3.org/2000/svg" p-id="5404" class="icon" data-v-a81d141e><path d="M526.60727968 10.90185116a27.675 27.675 0 0 0-29.21455937 0c-131.36607665 82.28402758-218.69155461 228.01873535-218.69155402 394.07834331a462.20625001 462.20625001 0 0 0 5.36959153 69.94390903c1.00431239 6.55289093-0.34802892 13.13561351-3.76865779 18.80351572-32.63518765 54.11355614-51.75690182 118.55860487-51.7569018 187.94566865a371.06718723 371.06718723 0 0 0 11.50484808 91.98906777c6.53300375 25.50556257 41.68394495 28.14064038 52.69160883 4.22606766 17.37162448-37.73630017 42.14135425-72.50938081 72.80769204-103.21549295 2.18761121 3.04276886 4.15646224 6.24463696 6.40373557 9.22774369a1871.4375 1871.4375 0 0 0 140.04691725 5.34970492 1866.36093723 1866.36093723 0 0 0 140.04691723-5.34970492c2.24727335-2.98310674 4.21612437-6.18497483 6.3937923-9.2178004 30.66633723 30.70611158 55.4360664 65.4791928 72.80769147 103.21549355 11.00766384 23.91457269 46.15860503 21.27949489 52.69160879-4.22606768a371.15156223 371.15156223 0 0 0 11.514792-91.99901164c0-69.36717486-19.13165746-133.82216804-51.75690182-187.92578088-3.42062944-5.66790279-4.76302748-12.26056868-3.76865837-18.80351632a462.20625001 462.20625001 0 0 0 5.36959269-69.943909c-0.00994388-166.08943902-87.32547796-311.81420293-218.6915546-394.09823051zM605.93803103 357.87693858a93.93749974 93.93749974 0 1 1-187.89594924 6.1e-7 93.93749974 93.93749974 0 0 1 187.89594924-6.1e-7z" p-id="5405" data-v-a81d141e></path><path d="M429.50777625 765.63860547C429.50777625 803.39355007 466.44236686 1000.39046097 512.00932183 1000.39046097c45.56695499 0 82.4922232-197.00623328 82.5015456-234.7518555 0-37.75494459-36.9345906-68.35043303-82.4922232-68.34111062-45.57627738-0.00932239-82.52019037 30.59548842-82.51086798 68.34111062z" p-id="5406" data-v-a81d141e></path></svg></div><canvas id="vuepress-canvas-ribbon"></canvas><div class="my-popup" style="display:none;" data-v-3414bdeb><div class="my-popup-container" data-v-3414bdeb><div class="my-popup-exit" data-v-3414bdeb></div> <img src="" alt data-v-3414bdeb></div></div><div data-v-2ebabc0c></div><div class="kanbanniang" data-v-3b0f9b07><div class="banniang-container" style="display:;" data-v-3b0f9b07><div class="messageBox" style="right:68px;bottom:230px;display:none;" data-v-3b0f9b07>
      欢迎来到 KnightSama‘s Blog
    </div> <div class="operation" style="right:90px;bottom:40px;display:;" data-v-3b0f9b07><i class="kbnfont kbn-ban-home ban-home" data-v-3b0f9b07></i> <i class="kbnfont kbn-ban-message message" data-v-3b0f9b07></i> <i class="kbnfont kbn-ban-close close" data-v-3b0f9b07></i> <a target="_blank" href="https://vuepress-theme-reco.recoluan.com/views/plugins/kanbanniang.html" data-v-3b0f9b07><i class="kbnfont kbn-ban-info info" data-v-3b0f9b07></i></a> <i class="kbnfont kbn-ban-theme skin" style="display:;" data-v-3b0f9b07></i></div> <canvas id="banniang" width="200" height="260" class="live2d" style="right:90px;bottom:-20px;opacity:0.9;" data-v-3b0f9b07></canvas></div> <div class="showBanNiang" style="display:none;" data-v-3b0f9b07>
    看板娘
  </div></div></div></div>
    <script src="/assets/js/app.a2483de7.js" defer></script><script src="/assets/js/4.0078dadf.js" defer></script><script src="/assets/js/1.c3e7d2b0.js" defer></script><script src="/assets/js/27.6ee3d263.js" defer></script>
  </body>
</html>
